A version of this story appeared in the March 23 edition of CNN’s Coronavirus: Fact vs. Fiction newsletter. Sign up here to receive the need-to-know headlines every weekday.

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Public health officials are watching in horror as millions of spring breakers hit beaches and ski resorts in America

Yes, the number of vaccinated people is rising steadily across the US But right now, experts say, it is critical to double down on attempts to lower Covid-19 case numbers. That means staying at home, wearing a mask and avoiding crowds.

Doctors worry that since not enough people are protected against the virus yet – only about 13.5% of the US population is fully vaccinated – the virus will continue to spread rapidly. That will give it more opportunities to mutate, and so increase the risk of a new variant emerging that could make the vaccine less effective.

Public health officials are urging Americans to delay travel, but people are hitting the road anyway. The Transportation Security Administration screened more than 1.5 million people at airports nationwide on Sunday – a new pandemic-era record, and the 11th straight day that it has screened more than a million people. And some states are continuing to lift restrictions – even as case numbers remain high.

Centers for Disease Control and Prevention director Dr. Rochelle Walensky said the White House is encouraging governors, as well as the private sector, to maintain or reimpose coronavirus restrictions.

“We must act now, and I am worried that if we don’t take the right actions now, we will have another avoidable surge – just as we are seeing in Europe right now and just as we are so aggressively scaling up vaccination,” she said.

Europe is a cautionary tale. Several countries across the continent have been overwhelmed by new, more infectious variants of the disease and forced into new lockdowns. This morning, German Chancellor Angela Merkel said she would extend the country’s lockdown to April 18 amid a sharp spike in Covid-19 cases.

Cases are rising globally. The World Health Organization said yesterday that the number of new infections had risen for the fifth consecutive week.

YOU ASKED. WE ANSWERED.

Q: I am fully vaccinated. Can I visit my unvaccinated family and friends?

A: Yes, but visits should be limited to one unvaccinated household at a time, Centers for Disease Control and Prevention officials said yesterday.

“In the setting that the unvaccinated people are from a single household, and all the unvaccinated people are at low risk of severe Covid-19 illness, no prevention measures are needed, so these visits could happen indoors with no mask or physical distancing,” said CDC epidemiologist Tami Skoff.

Send your questions here. Are you a health care worker fighting Covid-19? Message us on WhatsApp about the challenges you’re facing: +1 347-322-0415.

WHAT’S IMPORTANT TODAY

AstraZeneca faces more questions in the US

US health officials have raised concerns over the results of AstraZeneca’s latest vaccine trial. The drug giant said its vaccine had 79% efficacy against symptomatic disease and 100% efficacy against severe disease and hospitalization in a new, US-based clinical trial.

A statement by the US National Institute of Allergy and Infectious Diseases said the Data and Safety Monitoring Board had “expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.”

AstraZeneca is expected to apply for emergency use authorization for its vaccine in the next few weeks.

Covid-19 vaccines are for sale on the dark web

Counterfeit vaccine cards and what are being billed as Covid-19 vaccines are for sale on the dark web, according to a new cybersecurity report. Security researchers at Check Point Software said they’ve discovered listings for Covid-19 vaccines from various brands, such as AstraZeneca and Johnson & Johnson, for up to $1,000 a dose, as well as at least 20 vaccine certificates for $200 each. Also for sale: negative Covid-19 test results for $25.

The dark web is a part of the internet not detected by search engines where cybercriminals often sell and buy illicit materials, from credit card numbers and drugs to cyberweapons and now, apparently, coronavirus-related products.

Ontario in the third wave amid worries about slow vaccine rollout

Health officials in Ontario, Canada’s largest province, have warned the third wave of the coronavirus pandemic has started. Case numbers and hospitalizations are increasing as new variants of the virus continue to spread.

Public health officials have warned that the vaccine rollout isn’t going quickly enough to halt a potentially devastating third wave in other areas of the country. Prime Minister Justin Trudeau said yesterday that vaccine shipments would continue to ramp up, but officials are now faced with the possibility that the vaccines will not be distributed in time to avoid a significant number of hospitalizations and deaths.

ON OUR RADAR

  • Russian President Vladimir Putin is finally getting vaccinated – months after he became eligible for a shot.
  • The gap between the number of Covid-19 vaccines administered in rich and poor countries is growing and becoming “more grotesque” every day, the WHO chief says.
  • A leading opposition candidate in the Republic of Congo’s presidential election has died from Covid-related complications, a day after the vote.
  • US administration officials are not confident that Johnson & Johnson will meet its self-imposed deadline to deliver 20 million coronavirus vaccines by the end of March, despite optimistic statements from the company.
  • Anyone trying to travel abroad from England next week will need a “reasonable excuse” or face a fine of nearly $7,000 (£5,000), according to new proposed legislation.
  • More women than men skipped health care services during the pandemic, according to a report released Monday by the Kaiser Family Foundation.
  • As young people itch to leave lockdown, British health leaders face a new challenge: Social media influencers enjoying the sun in Dubai.

TOP TIPS

Humans have never been so dependent on technology as this past year. Some of it has been fun and brilliant, some of it an exhausting battle for attention.

Dr. Jenny Radesky, a developmental behavioral pediatrician, says this is a time to reflect on what worked and what didn’t, and how we need to move forward. Here are her main takeaways from the digital immersion we and our children have experienced over the past year.

TODAY’S PODCAST

“We can save more lives if we’re sharing vaccines.” – Dr. Krishna Udayakumar, director of Duke University’s Global Health Innovation Center

As wealthier nations have bought up most of the world’s supply of vaccines, many lower- and middle-income countries have been left behind. CNN’s Chief Medical Correspondent Dr. Sanjay Gupta speaks to Dr. Krishna Udayakumar about the challenges of getting the vaccine to everyone around the world. Listen now.